Method for forging insulator caps



Feb. 21, 1933. I c. s, CARD 4 METHOD FOR FORGING INSULA'I'OR CAPS FiledMa 12, 19:50 -2 shuts-sheet 1 ll/A INVENTOR.

CHARLES 5.. (4P2.

A T-TORNEY.

Feb. 21, 1933. c, s, CARD 1,898,574

METHOD FOR FORGING TO S Patented Feb. 21, 1933 UNITED STATES PATENTOFFICE CHARLES S. CARD, CORTLAND, NEW YORK, ASSIGNOR TO THEBREWER-TITOHENEB CORPORATION, OF CORTLAND, NEW YORK, A CORPORATION OFNEW YORK METHOD FOR FORGING INQULATOR CAPS Application filed May 12,1930. serial No. 451,581.

This invention relates to the art of. hollowed metal forgings and moreparticularly to the production of a one-piece cap or bellshaped socketadapted to securely mount therein the neck of an insulator disk of themultiple suspension type as used in connection with high-tensionelectric transmission lines or the like. My invention in certainparticulars represents a refinement in method of fabrication over thedisclosure made in the Clinton W. Stover Patent 1,463,601 as grantedJuly 13, 1923.

The primary object of my improved method is to effectively andeconomically fabricate a perfectly sound chambered product of thischaracter, which will consistently be relatively flawless in metalstructure especially as practiced by the drop-forged process where theaction is impactive or percussive as distinguished for instance from amore sustained pressure as appliedin the case of a steam hammer orhydraulic press. The present method of making such insulator capsinvolves among other things, an improved blanking operation preferablyby the dropforging method, that allows of working up a relatively largecup-shaped forging out of comparatively small bar-stock. Said operationalso facilitates the shaping up of a uniform skirt wall thickness and ofotherwise holding the cap to exacting specifications, notwithstandingthat the exterior of the cap dome is provided with a heavy integralsuspension forming lug means forged to a thickness considerably greaterthan that given the said skirt wall and which lug means preferablypermits of completing the lug formation by machining surplus stock outof such solid dome metal.

The blank for making my cap is purposely carried through a series ofdifferent shapes prior to blocking out of the blank into a cupshape, andone of such supplemental re-shaping steps includes a flatteningoperation de-. signed to repeatedly work the blank central region andthus insure a more nearly flawless swaging for the aforesaid thickenedsolid domemetal.

A further object is to provide in a drop forging operation, meanswhereby the relonger life and to so carry out the stepsof my method,that the various integral sections of my gang die block may all be madeto wear out at an approximately uniform rate rather than have any onesuch section of the needed costly dies, wear at a relative ly fasterrate and thus require the premature discarding of the entire gang block.

Die charges represent a considerable item of expense in the forging ofinsulator caps, and I have found that because of the inherently limitedintensity given to the series of rapidly repeated blows, the successfulcarrying out of the drop-forge process by the use of board-lift hammersor the like, may be materially improved by a significant change inmethod over that heretofore practiced in connection with hydraulic orsteam hammers, or the like where high pressure of controllable intensityis gradually applied. An important advantage of the present adaptationto drop-forged purposes lies in greatly increasing the rate offabrication obtainable from a given press and in correspondinglyreducing the labor and other production costs to a level that will placethe forged product upon a competitive price basis with the moreconventional caps of the cast malleable iron type.

To this end and the accomplishment of other new and useful results, myinvention also consists in novel features of'stock manipulation and diestructure, all of which will hereinafter be more fully set forth.

Reference is had to the accompanying two sheets of drawings which areillustrative of a specific embodiment of my invention, particularly asapplied to drop-forged insulator caps, in which drawings: I

Fig. l is a sectional elevational view of an insulator cap assembly ofthe ear-suspension type.

Fig. 2 shows a perspective view of the billet or square bar stock fromwhich a cap may be forged.

Fig. 3 is a side elevation of a ram and die block members showing thembrought into operative raised relationship.

Fig. 4 represents a top face view of the line 4-4 of Fig. 3, while Fig.5 is a bottom face view of the companion top block as seen from the line5-5 of Fig.3.-

Fig. 6 illustrates a sectional vertical view through the assembledblocks when brought into cooperative relationship as taken along theline 6-6 of Figs. 4 and 5.

Figs. 7, 8 and 9 are similar sectional block views as taken along line7-7, 8-8, and 99 respectively.

F ig. 10 shows in perspective a roller type of impression that isinitially shaped up in the first of my die compartments, while Fig. 11is a perspective of the blank that is formed therefrom.

Fig. 12 represents a sectional perspective view of the forging as itcomes from the blocker compartment of my die block, and Fig. 13 showsaid forging after it leaves the finishing compartment.

Fig. 14; illustrates a fragmental view of a modified or socketed dometype of cap which may be forged up in a substantially identical manner.

Fig. 15 is a cross-sectional view of the aforesaid impression as takenalong line 1515 of Fig. 10, while Fig. 16 is a similar view after suchimpression is flattened, as taken along line 16-16 of Fig. 11. 7

Referring now to Fig. 1, this shows one member adapted to make up achain of petticoat insulator discs such as 10, of which the uppermost isordinarily suspended in any suitable manner from a transmission tower orthe like. The respective discs may be connected together in tandem bymeans of the interposed metal insulator caps such as 11, which cooperatewith oppositely disposed link-members such as 12, to constitute abuilt-up composite suspension insulator in the conventional fashion andof which the lowermost unit may be provided with a conductor clamp thatcarries the high tension transmission wire (not shown).

My invention seeks to promote quality and uniformity of product and ismore largely concerned with forging up said cap 11, which essentiallycomprises a flared tubular skirt portion 13 formed integrally with thedome portion 14. The dome shown in Fig. 1 is of the common clevis typeaffording a pair of spaced ears or straps such as 15 arranged topivotally receive a clevis type of adapter link 12, although theparticular mode of suspension is immaterial as far as the presentpurarticle. Figs. 3 to 9 inclusive illustrate a' compartmental bottomdie block 18 and a cooperating matrix or top die block 19 that is sunkin counter-part fashion. The respective die-blocks are here shown asequipped with four different compartments or heated recesses, of whichthe first may comprise a roller-like planchet forming chamber 20. Thecenter region of this particular recess as measured from the die partingface preferably provides for a semi-cylindrical cavity with across-sectionally oval stem depression disposed at either end thereof asindicated. This die element is adapted to press up a distortedegg-shaped impression or planchet 21 (see Fig. 10) which may be formedup from the rectangular metal bar stock 22 that is shown in Fig. 2. Thepurpose of this initial step is to neck-in one end portion of the barand gather suflicient stock in the overhanging bar extension to impart atransverse -cross sectional area to the body of said planchet (see Fig.15) that shall become enlarged rel ative to the original bar stock, tothe end that the body portion of the planchet 21 may be carried througha series of appropriate steps that admit of finally blocking out myblank into a flared skirted shape whose rim region shall be free fromincipient flaws, cold-shuts in the ultimate product and withoutrequiring the metal to be unduly strained during any one of thesuccessive forging steps. The

operative end of each die recess may be dished to provide for the usualsprue by which the hot forging is shifted into a different compartment.

As a second step, said planchet is subjected tour. As represented inFigs. 11 and 16, the

opposite side faces of this blank may be hollowed out somewhat betweenthe pairs of marginal stifi'ning ridges such as 25. The described blankcontour induces the forged metal to uniformly fill out the more distantdie interspaces. The use of such ridge means is not however essentialsince the cited flattening'action alone serves to more thoroughly workand thereby locally refine the metal lying in the centrally disposedbody region of the initial impression or planchet 21; this metal portionultimately forms up the thick dome wall element together with thesupporting ears of my cap structure and all of which must be madecapable of withstanding a heavy line load without rupture or incipientfailure.

As a third step, said blank 24 after being flattened as described, ispassed through the blocker compartment. The bottom die 18 thereof ispreferably bored out at 27 for the snug insertion of a replaceable plugwhich affords a rather blunt frustrum-like protuberance 28 adapted toinitially shape up the cap interior in cooperation with thecorresponding top die recess 29. It will be observed that the diametraldimension D given to my blank 24 is preferably kept somewhat larger thanthe top face of the cone frustrum 28 and that the flattened surface ofsuch blank is preferably made to wholly overlap the perimeter of saidtop face. After the blank 24 has been blocked up, it assumes theimpression designated as 30 in Fig. 12, from the dome exterior of whichimpression, there is extruded a potential ear forming lug whose shapeincludes a relatively narrow projecting boundary face having atrapezoidal profile.

Said impression is now passed through the finishing die compartment 31which may also comprise a replaceable plug entered into the lowerdie-block 18 having a cone frustrum I tip 32. This tip is shown as notso bluntly shaped and adapted to cooperate withthe correspondingdepression in the top die 16 for the purpose of reforming the capimpression 30 into the semi-finished bell shape generally represented inFig. 13 by the numeral'33 and in which shape, the potential ear lugperimeter may now be rooved or partially slotted in order to reduce theheft of the metal where a milling cut is to be made by subsequentlyslotting the suspension lug into spaced complementary ears of the kinddepicted in Fig. 1, it being preferred to forge a pair of roundedupstanding beads (see Fig. 13) between which to confine the saidindented groove and thus avoid the need for grinding 01f burrs orotherwise finishing any sharp strap edges after said lug has beenmachine slotted. Up to this point, all of the described forgingoperations are intended to be carried out in a single heat and it willbe observed that the dome portion 14 is forged rather heavy incomparison to the relatively thin and flared skirt walls 13.

It now remains to trim the flash and cause the rim region of the openmouth skirt to be crimped inwardly by any suitable die means. Inaddition, the thickened crown portion may be machined or otherwiseshaped up to provide for a pair of finished ears such as 15. Instead ofthe described clevis type of support, my cap may likewise be forged upand suitably machined to constitute a cap 34 of undercut socketed dometype such as illustrated in Fig. 14.

Having described my process in detail, further advantages accruingtherefrom may be more fully pointed out. In the use of drop hammersoperating with intermittent blows rather than sustained pressure, anundue number of repeated blows would be required if attempt were made toforge'the bar stock directly into a thoroughly worked product describedin connection with fabrieating the blank 24. Such practice leads toexcessive wear on part of certain compartments with the result that theremaining die recesses would at the same time become useless and soonrequire resinking or replacement by entirely new die equipment. It isfurther found that the plug elements 28 and 32 are likely to suffer fromsurface checks or even fracture, while with my improved design, itbecomes possible to individually replace such plug elements 28 and 32 ata moderate cost. Said insertable plugs also allow of more readilychanging the tip contour in order to hold the close tolerances that mustbe met in a product of this kind. Finally, the life of dies which do notinclude passing said egg-shaped planchet 21 through the blanking diecompartment 23 according to my invention, has heretofore proveninadequate under such heavy-duty service and hardly likely to producemore than half the perfect impressions that can be obtained by thesequence of steps embodied in my improved method. The inclusion of thenovel flattening step also tends to prevent the hot forging fromsticking in the relatively deep die-recesses and at the same timereduces die charges in the making of complicated forgings of this kind.

It is to be understood that in the structural details and mode ofmanipulation may be resorted to in carrying out my improved method ofmaking insulator caps or like bell-shaped forgings, all withoutdeparting from the spirit and scope of my invention heretofore describedand more particularly pointed out in the appended claims.-

I claim:

1. The method of forging from bar stock, a one-piece supportableinsulator cap of the undercut socketed type or the like, which methodconsists in swaging said stock into a relatively fiat blank having anelongated contour provided with a depressed central face region flankedby spaced ridges, and thereupon blocking o'ut sald blank into acup-shape comprising a skirt portion to which said ridges contributestock, said skirt being provided with a mouthed rim end adapted to besubsequently cupped inwardly while the closed end of the cup is formedwith a solid projection integral therewith.

2. The method of forging from bar stock, a onepiece supportableinsulator cap of the undercut socketed type or the like, which methodconsists in gathering said stock into an egg-shaped planchet, thenswaging said stock into a relatively flat blank having a spear-likecontour, and thereupon blocking out said blank into a cup-shapecomprising a relatively thick dome wall from which there is extruded anexteriorly disposed lug means for said cap.

3. The method of passing bar stock through compartmental die means andforging therevarious changes from a one-piece supportable insulator capor the like, which method consists in swaging said stock intosuccessively different shapes starting with an egg-like shape and ofwhich the last shape forms a relatively flat blank whose center regionhas been worked in a plurality of die compartments, and there-' by theuse of a plurality of such die compartments and of which shapes thefirst comprises an egg-like shape and the last a flattened blank, andthereupon passing said blank into still another compartment for thepurpose of blocking out said blank into cup-shape, whereby to equalizethe rate of die wear of all said die compartments.

5. The method of hot forging from barstock, in a' single heat, aone-piece insulator cap or the like, which method includes an initialstep. of gathering stock to form a planchet of distorted egg-shape whosemid transverse cross-sectional area is enlarged over that of theoriginal bar; thereupon, by the use of a separate supplementary swagingstep, flattening a surface region of the aforesaid planchet; and by theuse of still another step, blocking out such flattened planchet into acup-shape comprising a supportable dome portion to which saidsupplementary swaged metal contributes stock.

6. The method of forging from bar-stock, a one-piece insulator cap orthe like, which method includes an initial step of gathering stock toform a blank of distorted eg -like v shape, the mid-transversecross-sectional area of said shape being enlarged over that, of

' sulator cap or the like from bar-stock by the use of mated die-blockshaving a blocking compartment therebetween, which method consists ingathering said stock into a distorted egglike shape, the mid-transversearea of said'shape being enlarged over that of the original bar; andthen by the use of a su lementary swaging step transformin saiddistorted shape to proviiie for a blan havin a flattened surface region;and thereupon orming said blank into cup shape by means of the blockingcompartment provided with a chambered female block and a cooperatingmale block carrying a frustumlike projection that terminates in a blunttip face, the aforesaid surface region being sufficiently flattenedprior to blocking said blank that when superimposed upon the tip face,said surface region will lie contiguous to, and overlap the entireperimeter of, the aforesaid tip face.

8. The method of forging from bar-stock, a one-piece insulator cap orthe like provided with machine slotted supporting ears,

which method includes an initial step of gathering stock to form animpression of distorted egg-like shape, the mid-transversecross-sectional area of said shape being enlarged over that of theoriginal bar; therev upon by a supplemental swaging step, transformingsaid distorted shape'to provide for a flattened blank surface regionthat is centrally depressed and blocking out said fiattened blank intocup-shape from the closed dome exterior of which there is extruded asolid, polyfaced ear-forming lug which includes a relatively narrow,projecting boundary-face of trapezoidal profile; and then by the use ofstill another step, finishing said cup-shape and simultaneously groovinga portion of the aforesaid boundary-face lengthwise thereof tofacilitate the machine slotting" of said lug into spaced comple-.

